w124/250D Manual gearbox issue and Diff Question

[snoopy]

Firstly I sourced a diff for the car but it's a 3.91 and I most likely have a 3.64 on it at the moment. The car is flat as expected for a non-turbo and I was wondering how bad it's going to make it (I believe the 3.9 makes the engine run at less RPM for the same speed...)?

Secondly I'm having a bit of an issue getting first gear, sometimes. For the first time today I couldn't get it in that or second, only rolling the car a bit makes it go in so if I forget to do it before stopping it can be an issue. The other gears are slick. It's not all the time and normally just needs a little more push than the other gears. I also noticed in 1st/2nd if holding the gear stick it can jerk a bit through the stick though this may be unrelated and normal.

Just another problem to add to the list of my poor automotive cockroach.

 

[BlackC55]

Fit the correct diff. It will make it a nightmare to drive.

The clutch or clutch system may need some attention. Try bleeding the clutch first. The fluid maybe old.

 

[snoopy]

What will the 3.91 do? It is a manual and I've heard it doesn't have the issues that swapping for a non-standard in an auto has.

Finding a 3.64 is a nightmare, plenty in Germany but at cost...

 

[BlackC55]

Can you not get yours fixed?

 

[snoopy]

I have no idea. The WALALALLALALLA sound is louder than the engine.

 

[BlackC55]

You can get it fixed. Any decent gearbox repairer can do it.

 

[Sp!ke]

I was quoted £600 to repair the diff on my W201. A new diff is £800.

Neither are guaranteed to be quiet.

 

[219]

I was quoted over a grand for an ASD diff for my 300TE ( that was the exchange price from MB and just to supply - not fit ) .

I hunted for a used one - plenty of non ASD 300's were about but to change over would have involved changing driveshafts and a few other bits - in the end I just cut my losses and sold the car for spares as it owed me nothing after seven years and 150K .

 

[snoopy]

Am I right in saying the 3.91 will make it accel a bit quicker / engine runs higher at same speed?

 

[krimat2005]

yes, you are right!! but don't put 3,91 on your car!! try some brakers.

 

[snoopy]

I has a 3.67 diff on at the moment so I can't see the difference being massive.

It is quite underpowered and the extra low gearing would probably help. I also run 17" instead of 15" wheels so the 3.91 might put it closer to the original?

 

[krimat2005]

right, what size your tyres are? you can't expect much from 94bhp on car that weight about 1,5 tonne. you must remember if you change diff you need to change the speedometeer as well for that diff ratio. and once again don't swap for 3,91 diff you will be travelling at 70mph with around 4000rpm = ??? MPG !!!! with a top speed propably not more than 85??

 

[snoopy]

70mph in 5th is 3,000RPM or just over for the 250D manual. When going up an incline in this config 70mph is the maximum attainable speed.

I've fitted the 3.91 and the walalallal noise has stopped. Sadly the sensor snapped so it'll be coming back off. Unusually my ABS is working well without it but perhaps it has to be on the road not running on stands. I sense another previous owner bodge though. .

It had a 3.64 fitted, the 3.91 isn't going to make that much difference!

I have 17" wheels not low profile tyres. I don't know the diameter but they are bigger than standard.

 

[snoopy]

Also observed that the flanges are the same size but old one has grooves that look like they interconnect. New one doesn't therefore load would go all via the M10 bolts.

ABS sensor different (plastic not metal) it has snapped inside but the two metal bits still sticking out so I'm deliberating on drilling it out or soldering two wires on. There's no guaranty the metal one will fit.

 

[krimat2005]

first: if you have tyres bigger or smaller diameter than originals then your speedo is not accurate,
second: if you haven't change the speedometer after changing diff your speedo will be even more inacurate.
is 3000RPM at 70MPH with the 3,91 diff??

 

[snoopy]

The 3.91 is in and the noise has gone - TERRRRRIFIC! :bannana::bannana:
Haven't noticed much if any difference in acceleration.

3000RPM@70mph was with the 3.64. I haven't tested it with the 3.91 yet.

ABS is off as need to replace the sensor. Unsure if mine will fit though.

 

[krimat2005]

when you test it don't look at the speedo, check it with sat nav. don't know about sensor.

 

[snoopy]

Got lucky.

The w124 sensor works in the w202 diff. The sensor is higher quality than the w202 one which rusted inside.

The speedo says 54mph and GPS says 49/50mph.

 

[Druk]

The gear select problem might just be worn-out rubbers on the selector lever ends of the change rods.